While he's certainly an ally, Castiel's role in
"Supernatural" has never been the same as the Winchesters'. Castiel is usually more embroiled in the mythology and the broader, season-long arcs, while the Winchesters deal with the the more day-to-day standalone hunts on their own. When he
returns from Purgatory, though, Castiel is over the whole angel thing -- and he wants to join the boys on the road and become a hunter in his own right.

Suffice to say, Sam and Dean have their doubts. In the episode "Hunteri Heroici," which airs Wednesday, Nov. 28 at 9 p.m., they reluctantly agree to investigate a case that Castiel has found, in which a man's heart burst through his chest. Literally.

If that sounds like something that happens on a cartoon when a pretty girl walks past a lusty dude... you're pretty much on the right track. The Winchesters and Castiel happen upon a town where cartoon physics have replaced actual reality, and they face a bevy of dangers that probably wouldn't hurt a wascally wabbit for very long, but have disastrous consequences on humans. Think falling anvils and people running off of cliffs and not falling until they look down.